
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Created with IDEA
 * author:ju bai
 * Date:2021/3/2
 * Time:19:35
 **/

public class ReflectClassDemo {
    // 创建对象
    public static void reflectNewInstance() {
        try {
            //1、
            Class<?> cl = Class.forName("Student");
            //2、
            Student student = (Student)cl.newInstance();
            System.out.println(student);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        }
    }

    public static void reflectPrivateConstructor() {
        try {
            //1、
            Class<?> cl = Class.forName("Student");
            /*//2、获取的是不带有参数的构造方法
            Constructor<?> constructor = cl.getConstructor();
            Student student = (Student) constructor.newInstance();
            System.out.println(student);*/
            //getConstructor 获取的公有的构造方法
            //getDeclaredConstructor:获取的是所有的构造方法
            Constructor<?> constructor =
                    cl.getDeclaredConstructor(String.class,int.class);
            //以后再反射私有的东西的时候，如果要进行修改：setAccessible(true);
            constructor.setAccessible(true);
            Student student = (Student) constructor.newInstance("gaobo",18);
            System.out.println(student);



        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }


    public static void reflectPrivateField() {
        try {
            //1、
            Class<?> cl = Class.forName("Student");

            Field field = cl.getDeclaredField("name");
            field.setAccessible(true);

            Student student = (Student) cl.newInstance();
            System.out.println(student);

            field.set(student,"gaobo");

            System.out.println(student);
            System.out.println(field.get(student));


        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        }
    }


    public static void reflectPrivateMethod() {
        try {
            //1、
            Class<?> cl = Class.forName("Student");
            //2、
            Method method = cl.getDeclaredMethod("function",String.class);

            Method[] methods =  cl.getDeclaredMethods();


            method.setAccessible(true);
            Student student = (Student) cl.newInstance();

            method.invoke(student,"我是参数！");



        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }


    public static void main(String[] args) {
        //reflectNewInstance();

        //reflectPrivateConstructor();

        //reflectPrivateField();

        reflectPrivateMethod();
    }
}

